Have you watched House of the Dragon yet? It's a TV show about the Targaryens, the silver-haired human cousins of dragons who ruled Westeros for 300 years. If you still have no clue, they are Daenerys Targaryen and Jon Snow's forefathers.
People who have watched Game of Thrones have seen Dany's backbreaking rise to power and then her slipping into madness, her romance with her nephew-boyfriend Jon Snow, and her eventual heartbreaking death.
But where did it all start? Who were the Targaryns, and what was the world like when they ruled? All these questions were answered in the Game of Thrones prequel, House of the Dragon. The series is set 200 years before the events of Game of Thrones and shows why the world needed the Targaryen race to end.
If the concept of dysfunctional families were on steroids, it would be House of the Dragon. The show has everything: bloated royal egos, bad parenting, petty fights, sibling rivalry that would put Cain and Abel to shame, and loads of dragons. Everything above became a catalyst in the downfall of a majestic dynasty. Let's find out in detail.
How House of the Dragon sets up the Targaryen downfall in Game of Thrones
Put a finger down if your family ruled the seven kingdoms, with dragons serving you and the whole Westeros bowing at your feet, but you still managed to lose all power. All Targaryen fans assemble, because today you will get to know how the Targaryens lost all glory, and to know that, let's go back 200 years, where the foundation of their downfall was laid.
1) Targaryens were the kings of self-sabotage

Who needs enemies when you have a brain like the Targaryens? They were their own worst enemies, and a significant reason for their downfall was the decision they made. In House of the Dragon, King Viserys I is shown to be a noble king, but when he decided to name Rhaenyra as his heir, it irked a lot of people in his court.
No matter how progressive that decision sounds, it was not something that came easily during medieval times. After his death, the battle for the Iron Throne began with Queen Alicent Hightower (Viserys' second wife) and her loyalists (the greens) crowning her son Aegon II as the new king.
While another faction (the blacks) that was loyal to Viserys' firstborn, Princess Rhaenyra, declared her as the rightful heir. The war between siblings came to be known as the Dance of the Dragons and fractured the House Targaryen into fragments that festered for the years to come.
2) Targaryens lost their dragons

Targaryens were feared all over Westeros because of their dragons; it was the only reason they ruled the seven kingdoms without anyone plotting to murder them (unless it was a family member). But instead of preserving these majestic wonders, they began using them as their war machines.
In the House of the Dragon, the Targaryens split into two factions, and a war for succession ensues between Aegon II and Princess Rhaenyra. With each battle, a majestic beast is turned into a crispy nugget.
Once all the dragons were lost, the Targaryens were seen as just another house that could be overthrown, and that is exactly what happened. By the time Game of Thrones came to light, there were none left. That is, until Dany came along; the poor girl had to burn herself to bring them back.
3) The Targaryens didn't tell anyone about the White Walkers

In the House of the Dragon, King Viserys I reveals a prophecy to Rhaenyra according to which a Targaryen must sit on the Iron Throne to save humanity from an impending darkness. He meant the White Walkers. And as everyone saw, 17 years after King Ares was overthrown and killed, the White Walkers surfaced and gained power.
But here is the deal: if a person knows about an imminent threat, should it become common knowledge? If people are warned about any upcoming dangers beforehand, they can prepare for them and be ready when they surface. The prophecy was passed down as a family secret recipe and guarded more than life itself.
Daenerys Targaryen and Jon Snow bore the brunt of this years later. One lost their life, and the other lost his rightful kingdom.
4) Targaryen superiority complex

The Targaryens weren't originally from Westeros; they were from Valyria and were very proud of their heritage. Their silver hair and their dragon blood set them apart from the Westerosi, and it was something they felt made them superior. It was one of the reasons that they preferred 'marrying within the family' rather than choosing mates from other great houses.
This resulted in houses like Stark, Arryn, and Tully creating alliances to defeat the Targaryens, and once all of their dragons died, it became possible to do so.
5) Targaryens were vulnerable without the dragon

The entire charade of Targaryen superiority was because of their dragons; without them, they were just another house. If you keep the dragons aside for one second, you will notice that each generation of Targaryens was worse at ruling than the last (with a few exceptions, of course). They were either turning mad or disappearing into oblivion. All this because their power was based on dragons instead of competence.
The beginning of the end was clear in the House of the Dragon, where successors were chosen via politics or battle instead of following tradition. It showed how two factions were created who constantly undermined each other in front of the entire Westeros, not realizing that they were undermining the Targaryen legitimacy in the process.
So, what did House of the Dragon teach its fans? It taught everyone that the Targaryens were mighty, intelligent, had awesome hair, and needed therapy. The downfall was slow, tragic, but inevitable. People blame the Mad King for their downfall, but House of the Dragon shows everyone it began much earlier than that.
The Targaryens were blessed with royalty and mighty beasts and also cursed with fire prophecies, bad decisions, and a bad temper. Maybe it was the inbreeding. Whatever the reason, a glorious dynasty that could have carved a much better history for itself saw a dreadful end. So, next time you think your family is bad, be happy that yours didn't end an empire.